<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			* {
				padding: 0px;
				margin: 0px;
				list-style: none;
				text-decoration: none;
				/* 可以把所有元素变为怪异盒子，方便布局 */
				box-sizing: border-box;
			}
			
			.div {
				border-radius: 50%;
				background-color: #f00;
				height: 100px;
				width: 100px;
			}
		</style>
	</head>
	<body>
		<div class="div">
			
		</div>
	</body>
</html>